EnC support for source-generated files

BenchmarkDotNet.Artifacts/results/IdeCoreBenchmarks.ProjectOperationBenchmarks.IterateDocuments-report-github.md

@@ -0,0 +1,20 @@
+``` ini
+
+BenchmarkDotNet=v0.12.1, OS=Windows 10.0.19042
+AMD Ryzen Threadripper 3960X, 1 CPU, 48 logical and 24 physical cores
+  [Host]     : .NET Framework 4.8 (4.8.4300.0), X64 RyuJIT
+  DefaultJob : .NET Framework 4.8 (4.8.4300.0), X64 RyuJIT
+
+
+```
+|                    Method | DocumentCount |            Mean |         Error |        StdDev |          Median |  Gen 0 |  Gen 1 | Gen 2 | Allocated |
+|-------------------------- |-------------- |----------------:|--------------:|--------------:|----------------:|-------:|-------:|------:|----------:|
+|       **Project.DocumentIds** |             **0** |        **23.34 ns** |      **0.494 ns** |      **0.891 ns** |        **22.91 ns** |      **-** |      **-** |     **-** |         **-** |
+|         Project.Documents |             0 |        77.22 ns |      0.537 ns |      0.502 ns |        77.31 ns | 0.0772 |      - |     - |     128 B |
+| Solution.WithDocumentText |             0 |        14.60 ns |      0.324 ns |      0.690 ns |        14.57 ns |      - |      - |     - |         - |
+|       **Project.DocumentIds** |           **100** |     **8,159.41 ns** |     **10.113 ns** |      **8.965 ns** |     **8,157.79 ns** | **0.0305** |      **-** |     **-** |      **72 B** |
+|         Project.Documents |           100 |    16,356.60 ns |     97.365 ns |     91.076 ns |    16,382.64 ns | 0.0916 |      - |     - |     201 B |
+| Solution.WithDocumentText |           100 |    14,436.90 ns |    355.846 ns |  1,015.248 ns |    14,392.68 ns | 0.8240 | 0.2136 |     - |    5285 B |
+|       **Project.DocumentIds** |         **10000** |   **863,988.25 ns** |  **1,297.511 ns** |  **1,213.693 ns** |   **863,625.88 ns** |      **-** |      **-** |     **-** |      **80 B** |
+|         Project.Documents |         10000 | 1,861,933.16 ns | 11,538.506 ns | 10,793.125 ns | 1,859,064.65 ns |      - |      - |     - |     208 B |
+| Solution.WithDocumentText |         10000 |    14,088.55 ns |    281.041 ns |    453.828 ns |    14,003.49 ns | 0.8698 | 0.2289 |     - |    5539 B |

BenchmarkDotNet.Artifacts/results/IdeCoreBenchmarks.ProjectOperationBenchmarks.IterateDocuments-report.csv

@@ -0,0 +1,10 @@
+Method,Job,AnalyzeLaunchVariance,EvaluateOverhead,MaxAbsoluteError,MaxRelativeError,MinInvokeCount,MinIterationTime,OutlierMode,Affinity,EnvironmentVariables,Jit,Platform,PowerPlanMode,Runtime,AllowVeryLargeObjects,Concurrent,CpuGroups,Force,HeapAffinitizeMask,HeapCount,NoAffinitize,RetainVm,Server,Arguments,BuildConfiguration,Clock,EngineFactory,NuGetReferences,Toolchain,IsMutator,InvocationCount,IterationCount,IterationTime,LaunchCount,MaxIterationCount,MaxWarmupIterationCount,MinIterationCount,MinWarmupIterationCount,RunStrategy,UnrollFactor,WarmupCount,DocumentCount,Mean,Error,StdDev,Median,Gen 0,Gen 1,Gen 2,Allocated
+Project.DocumentIds,DefaultJob,False,Default,Default,Default,Default,Default,Default,111111111111111111111111111111111111111111111111,Empty,RyuJit,X64,8c5e7fda-e8bf-4a96-9a85-a6e23a8c635c,.NET 4.8,False,True,False,True,Default,Default,False,False,False,Default,Default,Default,Default,Default,Default,Default,1,Default,Default,Default,Default,Default,Default,Default,Default,16,Default,0,23.34 ns,0.494 ns,0.891 ns,22.91 ns,0.0000,0.0000,0.0000,0 B
+Project.Documents,DefaultJob,False,Default,Default,Default,Default,Default,Default,111111111111111111111111111111111111111111111111,Empty,RyuJit,X64,8c5e7fda-e8bf-4a96-9a85-a6e23a8c635c,.NET 4.8,False,True,False,True,Default,Default,False,False,False,Default,Default,Default,Default,Default,Default,Default,1,Default,Default,Default,Default,Default,Default,Default,Default,16,Default,0,77.22 ns,0.537 ns,0.502 ns,77.31 ns,0.0772,0.0000,0.0000,128 B
+Solution.WithDocumentText,DefaultJob,False,Default,Default,Default,Default,Default,Default,111111111111111111111111111111111111111111111111,Empty,RyuJit,X64,8c5e7fda-e8bf-4a96-9a85-a6e23a8c635c,.NET 4.8,False,True,False,True,Default,Default,False,False,False,Default,Default,Default,Default,Default,Default,Default,1,Default,Default,Default,Default,Default,Default,Default,Default,16,Default,0,14.60 ns,0.324 ns,0.690 ns,14.57 ns,0.0000,0.0000,0.0000,0 B
+Project.DocumentIds,DefaultJob,False,Default,Default,Default,Default,Default,Default,111111111111111111111111111111111111111111111111,Empty,RyuJit,X64,8c5e7fda-e8bf-4a96-9a85-a6e23a8c635c,.NET 4.8,False,True,False,True,Default,Default,False,False,False,Default,Default,Default,Default,Default,Default,Default,1,Default,Default,Default,Default,Default,Default,Default,Default,16,Default,100,"8,159.41 ns",10.113 ns,8.965 ns,"8,157.79 ns",0.0305,0.0000,0.0000,72 B
+Project.Documents,DefaultJob,False,Default,Default,Default,Default,Default,Default,111111111111111111111111111111111111111111111111,Empty,RyuJit,X64,8c5e7fda-e8bf-4a96-9a85-a6e23a8c635c,.NET 4.8,False,True,False,True,Default,Default,False,False,False,Default,Default,Default,Default,Default,Default,Default,1,Default,Default,Default,Default,Default,Default,Default,Default,16,Default,100,"16,356.60 ns",97.365 ns,91.076 ns,"16,382.64 ns",0.0916,0.0000,0.0000,201 B
+Solution.WithDocumentText,DefaultJob,False,Default,Default,Default,Default,Default,Default,111111111111111111111111111111111111111111111111,Empty,RyuJit,X64,8c5e7fda-e8bf-4a96-9a85-a6e23a8c635c,.NET 4.8,False,True,False,True,Default,Default,False,False,False,Default,Default,Default,Default,Default,Default,Default,1,Default,Default,Default,Default,Default,Default,Default,Default,16,Default,100,"14,436.90 ns",355.846 ns,"1,015.248 ns","14,392.68 ns",0.8240,0.2136,0.0000,5285 B
+Project.DocumentIds,DefaultJob,False,Default,Default,Default,Default,Default,Default,111111111111111111111111111111111111111111111111,Empty,RyuJit,X64,8c5e7fda-e8bf-4a96-9a85-a6e23a8c635c,.NET 4.8,False,True,False,True,Default,Default,False,False,False,Default,Default,Default,Default,Default,Default,Default,1,Default,Default,Default,Default,Default,Default,Default,Default,16,Default,10000,"863,988.25 ns","1,297.511 ns","1,213.693 ns","863,625.88 ns",0.0000,0.0000,0.0000,80 B
+Project.Documents,DefaultJob,False,Default,Default,Default,Default,Default,Default,111111111111111111111111111111111111111111111111,Empty,RyuJit,X64,8c5e7fda-e8bf-4a96-9a85-a6e23a8c635c,.NET 4.8,False,True,False,True,Default,Default,False,False,False,Default,Default,Default,Default,Default,Default,Default,1,Default,Default,Default,Default,Default,Default,Default,Default,16,Default,10000,"1,861,933.16 ns","11,538.506 ns","10,793.125 ns","1,859,064.65 ns",0.0000,0.0000,0.0000,208 B
+Solution.WithDocumentText,DefaultJob,False,Default,Default,Default,Default,Default,Default,111111111111111111111111111111111111111111111111,Empty,RyuJit,X64,8c5e7fda-e8bf-4a96-9a85-a6e23a8c635c,.NET 4.8,False,True,False,True,Default,Default,False,False,False,Default,Default,Default,Default,Default,Default,Default,1,Default,Default,Default,Default,Default,Default,Default,Default,16,Default,10000,"14,088.55 ns",281.041 ns,453.828 ns,"14,003.49 ns",0.8698,0.2289,0.0000,5539 B

BenchmarkDotNet.Artifacts/results/IdeCoreBenchmarks.ProjectOperationBenchmarks.IterateDocuments-report.html

@@ -0,0 +1,37 @@
+<!DOCTYPE html>
+<html lang='en'>
+<head>
+<meta charset='utf-8' />
+<title>IdeCoreBenchmarks.ProjectOperationBenchmarks.IterateDocuments-20210223-114823</title>
+
+<style type="text/css">
+	table { border-collapse: collapse; display: block; width: 100%; overflow: auto; }
+	td, th { padding: 6px 13px; border: 1px solid #ddd; text-align: right; }
+	tr { background-color: #fff; border-top: 1px solid #ccc; }
+	tr:nth-child(even) { background: #f8f8f8; }
+</style>
+</head>
+<body>
+<pre><code>
+BenchmarkDotNet=v0.12.1, OS=Windows 10.0.19042
+AMD Ryzen Threadripper 3960X, 1 CPU, 48 logical and 24 physical cores
+  [Host]     : .NET Framework 4.8 (4.8.4300.0), X64 RyuJIT
+  DefaultJob : .NET Framework 4.8 (4.8.4300.0), X64 RyuJIT
+</code></pre>
+<pre><code></code></pre>
+
+<table>
+<thead><tr><th>             Method</th><th>DocumentCount</th><th>     Mean</th><th>  Error</th><th> StdDev</th><th>   Median</th><th>Gen 0</th><th>Gen 1</th><th>Gen 2</th><th>Allocated</th>
+</tr>
+</thead><tbody><tr><td>Project.DocumentIds</td><td>0</td><td>23.34 ns</td><td>0.494 ns</td><td>0.891 ns</td><td>22.91 ns</td><td>-</td><td>-</td><td>-</td><td>-</td>
+</tr><tr><td>Project.Documents</td><td>0</td><td>77.22 ns</td><td>0.537 ns</td><td>0.502 ns</td><td>77.31 ns</td><td>0.0772</td><td>-</td><td>-</td><td>128 B</td>
+</tr><tr><td>Solution.WithDocumentText</td><td>0</td><td>14.60 ns</td><td>0.324 ns</td><td>0.690 ns</td><td>14.57 ns</td><td>-</td><td>-</td><td>-</td><td>-</td>
+</tr><tr><td>Project.DocumentIds</td><td>100</td><td>8,159.41 ns</td><td>10.113 ns</td><td>8.965 ns</td><td>8,157.79 ns</td><td>0.0305</td><td>-</td><td>-</td><td>72 B</td>
+</tr><tr><td>Project.Documents</td><td>100</td><td>16,356.60 ns</td><td>97.365 ns</td><td>91.076 ns</td><td>16,382.64 ns</td><td>0.0916</td><td>-</td><td>-</td><td>201 B</td>
+</tr><tr><td>Solution.WithDocumentText</td><td>100</td><td>14,436.90 ns</td><td>355.846 ns</td><td>1,015.248 ns</td><td>14,392.68 ns</td><td>0.8240</td><td>0.2136</td><td>-</td><td>5285 B</td>
+</tr><tr><td>Project.DocumentIds</td><td>10000</td><td>863,988.25 ns</td><td>1,297.511 ns</td><td>1,213.693 ns</td><td>863,625.88 ns</td><td>-</td><td>-</td><td>-</td><td>80 B</td>
+</tr><tr><td>Project.Documents</td><td>10000</td><td>1,861,933.16 ns</td><td>11,538.506 ns</td><td>10,793.125 ns</td><td>1,859,064.65 ns</td><td>-</td><td>-</td><td>-</td><td>208 B</td>
+</tr><tr><td>Solution.WithDocumentText</td><td>10000</td><td>14,088.55 ns</td><td>281.041 ns</td><td>453.828 ns</td><td>14,003.49 ns</td><td>0.8698</td><td>0.2289</td><td>-</td><td>5539 B</td>
+</tr></tbody></table>
+</body>
+</html>

src/Compilers/Core/Portable/Emit/EditAndContinue/DefinitionMap.cs

@@ -25,9 +25,9 @@ protected readonly struct MappedMethod
             public readonly IMethodSymbolInternal PreviousMethod;
             public readonly Func<SyntaxNode, SyntaxNode> SyntaxMap;
 
-            public MappedMethod(IMethodSymbolInternal previousMethodOpt, Func<SyntaxNode, SyntaxNode> syntaxMap)
+            public MappedMethod(IMethodSymbolInternal previousMethod, Func<SyntaxNode, SyntaxNode> syntaxMap)
             {
-                PreviousMethod = previousMethodOpt;
+                PreviousMethod = previousMethod;
                 SyntaxMap = syntaxMap;
             }
         }
@@ -311,16 +311,10 @@ internal VariableSlotAllocator TryCreateVariableSlotAllocator(EmitBaseline basel
                 symbolMap = MapToMetadataSymbolMatcher;
             }
 
-            var previousMethod = mappedMethod.PreviousMethod;
-            if (previousMethod is null)
-            {
-                previousMethod = (IMethodSymbolInternal)symbolMap.MapDefinitionOrNamespace(topLevelMethod);
-            }
-
             return new EncVariableSlotAllocator(
                 symbolMap,
                 mappedMethod.SyntaxMap,
-                previousMethod,
+                mappedMethod.PreviousMethod,
                 methodId,
                 previousLocals,
                 lambdaMap,

src/Compilers/Core/Portable/Emit/SemanticEdit.cs

@@ -53,7 +53,7 @@ public struct SemanticEdit : IEquatable<SemanticEdit>
         /// </summary>
         /// <param name="kind">The type of edit.</param>
         /// <param name="oldSymbol">
-        /// The symbol from the earlier compilation, or null if the edit represents an addition or an update of the symbol from the previous compilation that exactly matches <paramref name="newSymbol"/>.
+        /// The symbol from the earlier compilation, or null if the edit represents an addition.
         /// </param>
         /// <param name="newSymbol">
         /// The symbol from the later compilation, or null if the edit represents a deletion.
@@ -74,7 +74,7 @@ public struct SemanticEdit : IEquatable<SemanticEdit>
         /// </exception>
         public SemanticEdit(SemanticEditKind kind, ISymbol? oldSymbol, ISymbol? newSymbol, Func<SyntaxNode, SyntaxNode?>? syntaxMap = null, bool preserveLocalVariables = false)
         {
-            if (oldSymbol == null && kind is not (SemanticEditKind.Insert or SemanticEditKind.Update))
+            if (oldSymbol == null && kind != SemanticEditKind.Insert)
             {
                 throw new ArgumentNullException(nameof(oldSymbol));
             }